JP2012203475A - Communication device and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device that is highly convenient while protecting a file.SOLUTION: A communication device 20 according to one embodiment includes a first interface 35, a wireless communication unit 21, and a memory unit 24. The memory unit 24 includes a first region PT1 used for first access from the first interface 35 and a second region PT2 used for second access from the wireless communication unit 21. Writing into the second region PT2 by the first access and writing into the first region PT1 by the second access are inhibited.

Description

  Embodiments described herein relate generally to a communication apparatus and a control method thereof.

Traditionally, the only host that controls resources. For example, in the case of an SD ^™ memory card mounted on a digital camera, only the digital camera controls the files in the SD memory card.

  However, in recent years, SD memory cards equipped with a wireless LAN function have appeared. In such a memory card, there are two hosts for the SD memory unit, a digital camera and a wireless LAN function. When these two hosts simultaneously access a file in the SD memory unit, the file management table is changed at the same time, and the file may be destroyed.

  Therefore, exclusive control is performed by the OS of the digital camera so that the SD memory unit cannot be accessed simultaneously from a plurality of hosts. Thus, access to the SD memory unit is limited to any one host.

  However, with the above configuration, the file can be prevented from being destroyed, but the usability of the SD memory card becomes very poor.

JP 2006-216011 A

  Provided are an easy-to-use communication device and a control method thereof while protecting a file.

  The wireless communication apparatus according to the embodiment includes a first interface, a wireless communication unit, and a memory unit. The memory unit includes a first area used for a first access from the first interface and a second area used for a second access from the wireless communication unit. Writing to the second area by the first access and writing to the first area by the second access are prohibited.

1 is a block diagram of a memory card according to a first embodiment. 1 is a block diagram of a memory card according to a first embodiment. 1 is a conceptual diagram of a memory space of a NAND flash memory according to a first embodiment. The schematic diagram of the master boot record which concerns on 1st Embodiment. 6 is a flowchart showing the operation of the digital camera according to the first embodiment. The flowchart which shows operation | movement of the radio | wireless communication part which concerns on 1st Embodiment. The schematic diagram of the radio | wireless communication which concerns on 1st Embodiment. The block diagram of the memory card concerning a 2nd embodiment. The block diagram of the memory card concerning a 2nd embodiment. The conceptual diagram of the memory space of the NAND type flash memory which concerns on 2nd Embodiment. 9 is a flowchart showing the operation of a file system controller according to the second embodiment. The conceptual diagram of the memory space of the NAND type flash memory which concerns on 2nd Embodiment. The conceptual diagram of the memory space of the NAND type flash memory which concerns on 2nd Embodiment. The schematic diagram of the radio | wireless communication which concerns on 3rd Embodiment. The conceptual diagram which shows the structure of SD command. 10 is a flowchart showing the operation of the memory card according to the third embodiment. 9 is a timing chart showing a data writing method according to the third embodiment. 9 is a timing chart showing a data reading method according to a third embodiment. The block diagram of the memory card concerning a 4th embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. In the description, common parts are denoted by common reference symbols throughout the drawings.

[First Embodiment]
The communication device and the control method thereof according to the first embodiment will be described below using an SD memory card as an example.

1. About configuration
1.1 About digital cameras
FIG. 1 is a block diagram of an SD memory card (hereinafter sometimes simply referred to as a memory card) according to the present embodiment and a digital camera in which the SD memory card is inserted.

  As shown in the figure, the digital camera 10 has a memory card 20. The memory card 20 is inserted into, for example, a card slot provided in the digital camera 10 and is wired to the SD host interface 11 of the digital camera 10. The SD host interface 11 manages communication between the digital camera 10 and the memory card 20. The digital camera 10 communicates with the memory card 20 via the SD host interface 11.

1.2 Memory card
The memory card 20 operates with power supplied from the digital camera 10 via the SD host interface 11. Details of the memory card 20 will be described with reference to FIGS. FIG. 2 is a block diagram of the memory card 20.

  As illustrated, the memory card 20 includes a wireless LAN chip 21, an SD device interface 22, a NAND controller 23, and a NAND flash memory 24.

  The NAND flash memory 24 stores data in a nonvolatile manner.

  The NAND controller 23 controls the operation of the NAND flash memory. That is, data writing, reading, erasing, and the like are performed on the NAND flash memory 24.

  The SD device interface 22 manages communication with the wireless LAN chip 21. That is, the SD device interface 22 transfers various commands and data from the wireless LAN chip 21 to the NAND controller 23, and transfers various commands and data from the NAND controller 23 to the wireless LAN chip.

  The wireless LAN chip 21 roughly includes a baseband chip 30, an RF (radio frequency) chip 40, and an antenna 50. The baseband chip 30 performs baseband processing of data transmitted and received by wireless LAN communication and issues instructions and data to the NAND controller 23. The RF chip 40 processes analog data transmitted and received by wireless LAN communication. The antenna 50 transmits and receives data. Each will be described below.

  The RF chip 40 includes an RF unit 41. The RF unit 41 transmits and receives a signal in a high frequency band used when performing communication on a wireless transmission path, and amplifies analog data to be transmitted and received. Then, data is transmitted or received from the antenna 50. The RF unit 41 is formed on an RF chip 40 that is separate from the baseband chip 30, for example.

  The baseband chip 30 includes a physical unit 31, a MAC (medium access controller) unit 32, a CPU (central processing unit) 33, a memory controller 34, an SD device interface 35, an SD host interface 36, an SRAM 37, and a NOR flash memory 38. I have. These are formed on the same substrate.

  The physical unit 31 performs processing on a physical layer of transmission data and reception data of wireless LAN communication. That is, when receiving a frame by the wireless LAN, the physical unit 31 performs A / D conversion on the reception signal (analog signal) given from the RF unit 40 to obtain a digital signal. Further, the digital signal is demodulated. That is, for example, orthogonal frequency division multiplexing (OFDM) demodulation and error correction decoding are performed to obtain a received frame. Then, the obtained received frame is output to the MAC unit 32.

  On the other hand, when transmitting a frame, the physical unit 31 receives a transmission frame from the MAC unit 32. Then, the received transmission frame is redundantly encoded and OFDM-modulated, further D / A converted to obtain an analog signal, and this analog signal is output to the RF chip 40 as a transmission signal. This transmission frame is wirelessly transmitted from the antenna 50 by the RF chip 40.

  The MAC unit 32 performs processing on the MAC layer of transmission data and reception data of wireless LAN communication. That is, the MAC unit 32 receives a received frame from the physical unit 31 when receiving a frame. Then, the MAC header is removed from the received frame to assemble the packet. Note that a packet is a data structure in which transmission / reception data is handled by a personal computer or the like, and a frame is transmission / reception data assembled so as to be communicable by wireless communication. When transmitting a frame, the packet is received from the CPU 33 or the SD host interface 11 of the digital camera 10. Then, a MAC header is attached to the packet to assemble a transmission frame, and this is output to the physical unit 31.

  The CPU 33 executes an operating system (OS) and controls the overall operation of the wireless LAN chip 21. The CPU 33 performs processing on transmission data and reception data by the wireless LAN. Also, a process for writing data received by the wireless LAN into the NAND flash memory 24, a process for reading data to be transmitted by the wireless LAN communication from the NAND flash memory 24, and transmitting the data are performed.

  The memory controller 34 controls access to the SRAM 37 and other memories (for example, SDRAM (synchronous DRAM) 25).

  The SRAM 37 and the SDRAM 25 hold reception data and transmission data. These may have any configuration capable of holding data, and may be other semiconductor memories or a storage device such as a hard disk other than the semiconductor memory.

  The NOR flash memory 38 stores data in a nonvolatile manner, and holds an OS executed by the CPU 33, for example.

  The SD device interface 35 manages communication with the digital camera 10. That is, the SD device interface 35 receives various commands and data from the SD host interface 11 of the digital camera 10, and transfers necessary data to the SD host interface 11.

  The SD host interface 36 manages communication with the NAND flash memory 24. That is, the SD host interface 36 transfers various commands and data to the SD device interface 22 and receives necessary data from the SD device interface 22.

  In the above configuration, the photos and moving images transferred from the digital camera 10 to the memory card 20 are stored in the SRAM 37 and the SDRAM 25 via the SD host interface 11 and the SD device interface 35. As described above, access to the SRAM 37 and the SDRAM 25 is performed via the memory controller 34.

  There are two transfer destinations of data stored in the SRAM 37 and the SDRAM 25. One is an external terminal (communication device having a wireless LAN communication function, such as a mobile phone, a PDA, or a PC) to which a wireless LAN is connected, and the other is a NAND flash memory built in the memory card 20. 24.

  When data is transferred to an external terminal using a wireless LAN, the data is processed by the CPU 33 and then output to the RF unit 41 through the MAC unit 32 and the physical unit 31. The data is finally transferred from the RF unit 41 to the antenna 50 and transmitted as a wireless LAN frame. When data is received from an external terminal, the reverse process is performed.

  When data is transferred to the NAND flash memory 24, the data is processed by the CPU 33 and then transferred to the NAND controller 23 via the SD host interface 36 and the SD device interface 22. The NAND controller 23 converts the received address from a logical address to a physical address, and writes the data to the NAND flash memory 24. When data is read from the NAND flash memory 24, the reverse process is performed.

  Note that processing required for wireless LAN communication can be performed by either software or hardware. If implemented by hardware, the function is executed by the MAC unit 32 and the physical unit 31, and if implemented by software, the function is executed by the CPU 33.

2. Management method of NAND flash memory 24
Next, a management method of the NAND flash memory 24 will be described with reference to FIG. FIG. 3 is a conceptual diagram showing a memory space of the NAND flash memory 24. In this example, a case where management is performed using a FAT (File Allocation Table) file system will be described as an example.

  As shown in the figure, the memory space of the NAND flash memory 24 roughly includes a master boot record (MBR) and a plurality (four in this example) of partitions PT1 to PT4.

  The MBR has a size of, for example, 512 bytes and holds information regarding the four partitions PT1 to PT4. More specifically, the NAND flash memory 24 is divided into four partitions PT1 to PT4, and the top cluster number of each partition PT1 to PT4 (in other words, the top address of each partition PT1 to PT4). Keep information. An area in which “0” data is written is provided between the MBR and the first partition PT1. This area and MBR are hidden sectors and are not visible to the user.

  Each of the partitions PT1 to PT4 includes a BIOS parameter block (BPB), FAT1, FAT2, a root directory entry (RDE), and a user area.

  The BPB holds information such as how many bytes each sector comprises, how many sectors a cluster comprises, the number of sectors FAT1, FAT2, and the number of RDE entries (sector number). The size of BPB is defined as 512 bytes in the FAT standard. BPB is provided in the top area of each partition PT1 to PT4. Therefore, the location (first sector number) of BPB can be grasped from the first cluster number of each partition PT1 to PT4 held in the MBR.

  The FAT1 holds information on which cluster is in use or unused, and cluster chain information. That is, the memory space is a set of spaces of a certain size called clusters. If the data (file) to be written is larger than the cluster size, it is divided and stored in cluster units. At this time, clusters to which data is written may not be continuous. That is, one piece of data is stored using a plurality of clusters that are separated in place. At this time, management data for managing to which cluster the data is divided and written (cluster chain) is stored in the FAT. FAT1 is stored in an address area continuous with BPB. Therefore, the location and size of FAT1 can be grasped from the information of BPB.

  FAT2 is a backup of FAT1. Which file is damaged can be detected from FAT1 and FAT2. FAT2 is stored in an address area continuous with FAT1. Therefore, the location and size of FAT2 can also be grasped from the information of BPB.

  The RDE holds information on files and directories on the root directory. That is, the RDE has a plurality of entries, and each entry holds information such as the name, top cluster, attribute, creation time, and file size of the file or directory on the root directory. RDE is stored in an address area continuous to FAT2. Accordingly, the location and size of the RDE can also be grasped from the BPB information.

  The above BPB, FAT1, FAT2, and RDE can be said to be management information for the FAT file system. The management information of each partition PT1 to PT4 is for managing information on the user area of each partition PT1 to PT4.

  The user area is an area for holding net user data, and a subdirectory is also provided in the user area.

  FIG. 4 is a schematic diagram showing the configuration of the MBR. As shown in the figure, a bootstrap loader is stored in the first area of the MBR, followed by information (such as the leading cluster number) and signatures of the partitions PT1 to PT4.

3. About operation
Next, operations of the digital camera 10 and the wireless LAN chip 21 configured as described above will be described.

3.1 Operation of digital camera 10
First, the operation of the digital camera 10 will be described with reference to FIG. FIG. 5 is a flowchart showing an operation when the digital camera 10 uses the NAND flash memory 24.

  First, when the digital camera 10 is activated (step S10), the processor in the digital camera 10 reads out the OS from the memory in the digital camera 10 and activates it (step S11).

  The OS executed by the processor of the digital camera 10 accesses the NAND flash memory 24, reads the MBR (step S12), and analyzes it (step S13).

  As a result of analyzing the MBR, when there are two or more partitions (step S14, YES), the OS mounts the first partition which is one of them as an area where data can be read and written (and erased) ( (Step S15). Mounting is the process of recognizing a partition. Other partitions are mounted as read-only areas (step S16). For example, in the example of FIGS. 3 and 4, the digital camera 10 can freely read and write (and erase) data from the first partition PT1, but the other second to fourth partitions PT2. With respect to .about.PT4, only data reading can be executed. That is, the digital camera 10 reads the FAT from the first partition PT1, and manages the first partition PT1 by this FAT. The digital camera 10 freely accesses the first partition PT1, and rewrites the FAT of the first partition PT1 according to the access contents. However, the FATs of the other partitions PT2 to PT4 cannot be rewritten.

  On the other hand, when there is only one partition (step S14, NO), the OS mounts the partition as an area where data can be read and written (and erased) (step S17).

3.2 Operation of the wireless LAN chip 21
Next, the operation of the wireless LAN chip 21 will be described with reference to FIG. FIG. 6 is a flowchart showing an operation when the wireless LAN chip 21 uses the NAND flash memory 24.

  First, when the wireless LAN chip 21 is activated (step S20), the processor (CPU 33) in the wireless LAN chip 21 reads out the OS from, for example, the NOR flash memory 38 and activates it (step S21).

  The OS executed by the processor 33 accesses the NAND flash memory 24, reads the MBR (step S22), and analyzes it (step S23).

  As a result of analyzing the MBR, when there are two or more partitions (step S24, YES), the OS is one of them, and the second partition different from the first partition described in FIG. Then, it is mounted as a writable (and erasable) area (step S25). Other partitions are mounted as areas that can only be read (step S26). For example, in the example of FIGS. 3 and 4, the digital camera 10 can freely execute reading and writing (and erasing) of data with respect to the second partition PT2, but the other first, third, and second For the four partitions PT1, PT3, PT4, only data reading can be executed. That is, the wireless LAN chip 21 reads the FAT from the second partition PT2, and manages the second partition PT2 by this FAT. Then, the wireless LAN chip 21 freely accesses the second partition PT2, and rewrites the FAT of the second partition PT2 according to the access contents. However, the FATs of other partitions PT1, PT3, and PT4 cannot be rewritten.

  On the other hand, if there is only one partition (step S24, NO), the OS mounts the partition as an area where data can be read and written (and erased) (step S27).

4). Effects according to this embodiment
As described above, with the configuration according to the present embodiment, it is possible to provide an easy-to-use communication device while protecting files. This effect will be described below.

  As an example, consider a method of accessing an SD memory connected to a conventional digital camera. There are two ways to access the SD memory: a method using a digital camera as a host to access via the SD interface and a method using a personal computer as a host to access via the USB interface. However, these hosts cannot access the resource (SD memory) at the same time. If you try to access at the same time, priority is given to access from a personal computer, and access from a digital camera is not possible.

  The reason why the exclusive control is provided in this way is to protect the file management table (the FAT1 and FAT2 areas of the FAT file system) that manages the storage location of the file. Suppose that a digital camera and a personal computer can simultaneously access the SD memory. Then, the OS installed in the digital camera and the OS installed in the personal computer separately acquire and hold the file management table. That is, file management tables having different contents are created on each OS. In this state, when each host writes the file management table to the SD memory, the file management table of the host (for example, digital camera) written later becomes effective, and the file information of the host (for example, personal computer) written immediately before is valid. Overwritten and invalidated.

  Consider the case of an SD memory card equipped with a wireless LAN chip. A digital camera in which such an SD memory card is inserted can not only take a picture but also receive a picture from another terminal via a wireless LAN. That is, there are two hosts in the SD memory. When two different hosts (digital camera and wireless LAN) perform file operations on one SD memory, a contradiction occurs in the file management table.

  Such a problem occurs in the same manner as the relationship between the digital camera and the personal computer described above. In other words, the two hosts try to control the file system separately for the NAND flash memory which is the data storage area of the SD memory card.

  Specifically, the OS mounted on the wireless LAN chip and the OS mounted on the digital camera respectively acquire the FAT areas that constitute the FAT 16 and FAT 32 which are file systems of the SD memory card. Each updates the FAT area, and after the update, writes it back to the NAND flash memory. As a result, only the latest file management table becomes valid, and the file information of the host written immediately before is overwritten and invalidated.

  In order to solve such a problem, a method of restricting writing from the digital camera while writing from the wireless LAN can be considered. However, in this method, it is not possible to take a picture with a camera during a period in which, for example, a huge moving image file is transferred using a wireless LAN. That is, the user waits until the file transfer by the wireless LAN is completed. Therefore, with this method, file transfer by wireless LAN is possible, but there is a problem in that shooting cannot be performed during that time, and usability becomes very poor.

  In this regard, in the configuration according to the present embodiment, the NAND flash memory 24 of the SD memory card 10 is divided into a plurality of partitions PT1 to PT4 in advance (see FIG. 3). Then, a FAT is prepared for each partition, and the information is stored in the MBR. In addition, a separate partition is assigned to each host for writing.

  Thereby, each host recognizes that the NAND flash memory 24 is divided into a plurality of areas. Each host can hold the FAT for the assigned partition, and can write data only to the assigned partition.

  For example, in FIG. 3, it is assumed that the first partition PT1 is assigned to the digital camera 10 and the second partition PT2 is assigned to the wireless LAN chip 21. Then, the digital camera 10 recognizes the existence of the first to fourth partitions PT1 to PT4 and can read data from these areas, but writing (and erasing) is performed only on the first partition PT1. I can do it. The wireless LAN chip 21 can read data from the first to fourth partitions PT1 to PT4, but can write (and erase) only to the second partition PT1.

  Therefore, the information (FAT) recorded by the digital camera 10 can be prevented from being rewritten by the wireless LAN chip 21, and the information (FAT) recorded by the wireless LAN chip 21 can be rewritten by the digital camera 10. Can be suppressed.

  In this way, by dividing a resource into a plurality of areas in advance, it is possible to clarify the areas that can be operated by each host. According to this method, writing from a plurality of hosts to the same address does not occur. Therefore, it is possible to safely operate the file without allowing the file system to be damaged while allowing access from a plurality of hosts.

  In this embodiment, the case where four partitions are provided has been described as an example. However, the number of partitions is not limited to four, and at least the number of hosts is sufficient. FIG. 7 shows a case where the number of partitions is two. As shown in the figure, the CPU 12 of the digital camera 10 holds the FAT of the first partition PT1, and write access of the digital camera 10 is permitted only to the first partition PT1. On the other hand, another digital camera 60 via the access point 61 holds the FAT of the second partition PT2, and write access of the digital camera 60 is permitted only to the second partition PT2.

[Second Embodiment]
Next, a communication device and a control method thereof according to the second embodiment will be described. In this embodiment, the NAND flash memory 24 is not divided into a plurality of areas in the first embodiment, but the file is protected by performing address conversion. Below, only a different point from 1st Embodiment is demonstrated.

1. About configuration
FIG. 8 is a block diagram of the memory card according to the present embodiment and the digital camera in which the SD memory card is inserted. FIG. 9 is a more detailed block diagram of the memory card.

  As shown in the drawing, the memory card 20 according to the present embodiment is provided with a file system controller 70 and an SD host interface 71 in the configuration described in the first embodiment, and an SD host interface 36 in the wireless LAN chip 21 is provided. It is abolished.

  The file system controller 70 receives access to the NAND flash memory 24 from the digital camera 10 and the wireless LAN chip 21. Then, address conversion is performed as necessary, and the address and data are output to the NAND controller 23 via the SD host interface 71 and the SD device interface 22. More specifically, when there is a write command for the same address from both the digital camera 10 and the wireless LAN chip 21, one address is converted into another different address. In addition, when a write command is issued from the other to the address holding one data of the digital camera 10 and the wireless LAN chip 21, the address corresponding to this write command is converted into another different address.

2. Memory space of NAND flash memory 24
Next, the memory space of the NAND flash memory 24 will be described with reference to FIG. FIG. 10 is a conceptual diagram showing a memory space of the NAND flash memory 24.

  As shown in the drawing, in the present embodiment, the memory space of the NAND flash memory 24 is managed by one FAT (FAT1, FAT2) without being divided into a plurality of partitions. That is, both the data from the digital camera 10 and the data from the wireless LAN chip 21 are managed by the same FAT.

3. About operation
Next, the operation of the memory card 20 according to the present embodiment will be described with reference to FIG. FIG. 11 is a flowchart that focuses particularly on the operation of the file system controller 70 when there is a write access to the NAND flash memory 24.

  As shown in the figure, when the file system controller 70 receives a write access from the digital camera 10 and / or the wireless LAN chip 21 (step S30), the file system controller 70 determines that the address overlaps with an access from another host. It is determined whether or not (step S31).

  The case where the address is duplicated is, for example, when both the digital camera 10 and the wireless LAN chip 21 have write access to the same address at the same time, or data from either the digital camera 10 or the wireless LAN chip 21. This corresponds to the case where a write access is made from the other side to the area holding. The latter can be determined by referring to the FAT read from the NAND flash memory 24.

  If the addresses are duplicated (step S31, YES), the file system controller 70 converts the address for write access (step S32). Then, a write command for the converted address is issued and output to the NAND controller 23 via the SD host interface 71 and the SD device interface 22 (step S33).

  If a write access is simultaneously made to the same address from both the digital camera 10 and the wireless LAN chip 21, the address for the write access from at least one of them is converted. If the address is converted only for access from the wireless LAN chip 21, a write command to the converted address is issued for the data from the wireless LAN chip 21. On the other hand, with respect to data from the digital camera 10, a write command to the address received from the digital camera 10 is issued without address conversion. The reverse is also true. In some cases, address conversion may be performed for both write accesses.

  In the case where the addresses are not duplicated, for example, when both the digital camera 10 and the wireless LAN chip 21 have write access to different addresses at the same time, or the digital camera 10 and the wireless LAN chip 21 have write access from one side. In this case, the address is not an area for holding data of the digital camera 10.

  In this case (step S31, NO), the file system controller 70 issues a write command to the address received from each host without performing address conversion (step S34) (step S35).

4). Effects according to this embodiment
According to this embodiment, the same effect as that of the first embodiment can be obtained. That is, in the configuration according to the present embodiment, the memory card 20 includes the file system controller 70. Each host does not own a file system, and the file system controller 70 manages the file system. In other words, the FAT is rewritten by the file system controller 70 and not by each host. At this time, when the same address area is accessed from a plurality of hosts, the file system controller 70 performs address conversion so that the same address area is not accessed.

  This situation is shown in FIGS. 12 and 13 are schematic views of the memory space of the NAND flash memory 24. FIG. For example, as shown in FIG. 12, it is assumed that there is simultaneous write access from the digital camera 10 and the wireless LAN chip 21 to the area R1 of the address ADD1. Then, in this case, as shown in FIG. 13, the file system controller 70 performs address conversion for the write access from one host (wireless LAN chip 21 in the example of FIG. 13). As a result, data from the wireless LAN chip 21 is written not in the area R1 but in the area R2 of the address ADD2. Then, the file system controller 70 records in the FAT that the data from the digital camera 10 exists in the area R1 and the data from the wireless LAN chip 21 exists in the area R2.

  As described above, by centrally managing the FAT by the file system controller 70, it is possible to cope with write access from a plurality of hosts while preventing file destruction.

  Note that it is not particularly necessary to store somewhere that the address has been converted and the writing has been executed. This is because the subsequent data can be read or erased by referring to the FAT and specifying the necessary data by the file name.

[Third Embodiment]
Next, a communication device and a control method thereof according to the third embodiment will be described. This embodiment relates to an example in which a file system controller is used as in the second embodiment. In the second embodiment, the SD command issued by the digital camera 10 and the wireless LAN chip 21 is a command based on a protocol different from the SD interface. Is embedded. Below, only a different point from 2nd Embodiment is demonstrated.

1. About the concept of this embodiment
First, the concept of this embodiment will be described with reference to FIG. FIG. 14 is a conceptual diagram showing a state in which write access to the digital camera 10 and the wireless LAN chip 21 is performed.

  As in the second embodiment, the OSs of the digital camera 10 and the wireless LAN chip 21 do not manage the file system. These OSs only issue file control commands to the file system controller 70. The commands issued at this time are SMB (Server Message Block) protocol (RFC 1001, 1002), FTP (File Transfer Protocol) protocol (RFC 697, 959, 1639, 2228, 2389, 2428, 2640, 3659), WebDAV ( Conforms to protocols that control files, such as the Web-based Distributed Authoring and Versioning protocol (RFC 2518).

  Protocols such as SMB, FTP, and WebDAV were originally protocols used by a plurality of hosts to control files on a server on TCP / IP. However, in the present embodiment, exclusive control of file access is realized by using these on the SD interface.

  For example, since the SMB client accesses a file owned by the SMB server, the SMB manages the file system in a batch, and the SMB client only issues an instruction to read and write the file to the server. In order to avoid inconsistencies in the file system. Even if a file creation command is issued from a plurality of clients, the command is exclusively controlled on the server side, so there is no contradiction in the file system. This is the same for FTP and WebDAV.

  In order to realize this function on the SD interface, the file system controller 70 plays the role of an SMB server, and hosts such as the digital camera 10 and the wireless LAN 21 behave as SMB clients. As a result, the SMB protocol using the SD interface is realized. Since the file system is controlled only by the file system controller 70 in charge of the SMB server, the file system is not destroyed even if accessed simultaneously from a plurality of hosts.

  Then, the OS of the digital camera 10 and the wireless LAN chip 21 encapsulates the SMB protocol in the CMD 56 which is one of the SD commands, and transmits / receives to / from the file system controller 70. FIG. 15 is a table showing the configuration of the command CMD56.

  The encapsulation of the SMB protocol by CMD56 will be described. The CMD 56 is a command called a vendor command, and the meaning of the command is an SD command that can be freely determined by each user. The CMD 56 is allowed to send and receive data after issuing a command. Encapsulating the SMB protocol in the CMD 56 means transmitting the SMB protocol as data transmitted following the CMD 56. FIG. 14 conceptually shows this. FIG. 17 to be described later is an image when the SMB protocol is encapsulated in the CMD 56, and shows that the host issues the SMB protocol in the data transfer processing unit after issuing the CMD 56.

  As described above, the file system controller 70 matches the file system.

2. About operation
Next, the operation of the memory card 20 in this embodiment will be described.

2.1 Basic operation
First, a basic operation will be described with reference to FIG. FIG. 16 is a flowchart showing a rough flow of an operation for accessing the NAND flash memory 24.

  As shown in the figure, first, the host (the OS of the digital camera 10 and / or the wireless LAN chip 21) issues file control commands such as data writing, reading, and erasing according to the SMB protocol (step S40). Of course, the FTP and WebDAV protocols may be followed, but the following description will be made taking the case of following the SMB protocol as an example.

  Subsequently, the host encapsulates the issued file control command in the CMD 56 of the SD command, that is, embeds it in the CMD 56, and transmits it to the file system controller 70 (step S41).

  The file system controller 70 extracts a file control command according to the SMB protocol from the received CMD 56 (step S42). Then, the file system controller 70 updates the FAT of the NAND flash memory 24 and issues an SD command (CMD17, CMD18, CMD24, CMD25, CMD38, etc.) corresponding to the taken-out file control instruction, and issues it to the SD host interface. 71 and output to the NAND controller 23 via the SD device interface 22 (step S43).

2.2 Specific examples of data writing
Next, a specific example of an operation when data is written will be described with reference to FIG. FIG. 17 is a time chart showing signal exchange when data is written from the digital camera 10 to the NAND flash memory 24. The same applies when the wireless LAN chip 21 is a host.

  As shown in the figure, first, the digital camera 10 issues a CMD 56 and transmits it to the file system controller 70. At this time, the digital camera 10 sets “0” in the Argument field of the CMD 56. When “0” is set in the Argument field of the CMD 56, this means that the protocol is transmitted from the client (digital camera 10 in this example) to the server (file system controller 70 in this example).

  Subsequently, the digital camera 10 issues data (write command) according to the SMB protocol and transmits it to the file system controller 70. Recognizing the write command, the file system controller 70 updates the file system (FAT) read from the NAND flash memory 24.

  Further, the digital camera 10 issues a CMD 56 and transmits it to the file system controller 70. At this time, the digital camera 10 sets “1” in the Argument field of the CMD 56. When “1” is set in the Argument field of the CMD 56, it means that the server side obtains a result indicating whether or not the protocol processing is successful.

  In response to the CMD 56, the file system controller 70 returns the processing result of the SMB protocol (for example, whether the file system has been updated) to the digital camera 10. If the processing result is normal, the digital camera 10 transfers the write data to the file system controller 70, and the file system controller 70 transfers this write data to the NAND flash memory 24.

2.3 Specific examples of data reading
The data read operation is basically the same as that at the time of writing. FIG. 18 is a time chart showing signal exchange when data is written from the digital camera 10 to the NAND flash memory 24. The same applies when the wireless LAN chip 21 is a host.

  At the time of reading, a read command is given from the digital camera 10 as the SMB protocol. If the file system controller 70 can normally process the SMB protocol, read data is transferred from the NAND flash memory 24 to the file system controller 70 and from the file system controller 70 to the digital camera 10.

3. Effects according to this embodiment
Even with the configuration according to the present embodiment, the same effect as the first embodiment can be obtained.

  Originally, protocols such as SMB, FTP, and WebDAV are network protocols used between machines installed on TCP / IP. In this embodiment, these protocols are used between the digital camera 10 and the file system controller 70 connected using the SD interface, and between the wireless LAN chip 21 and the file system controller 70. At this time, the digital camera 10 and the wireless LAN chip 21 are clients, and the file system controller 70 serves as a server.

  The SMB, FTP, and WebDAV protocols use TCP / IP as a lower protocol. However, in this embodiment, the digital camera 10 and the wireless LAN chip 21 are connected by an SD interface. Therefore, the CMD 56 of the SD command is used instead of TCP / IP.

  The CMD 56 is an SD command that can be freely used by each vendor. In this embodiment, SMB, FTP, and WebDAV protocols are encapsulated in this command to perform file transmission / reception, file list acquisition, file movement, and file deletion.

  Then, the file system controller 70 analyzes the SMB protocol encapsulated by the CMD 56 of the SD command, and controls the NAND flash memory 24 according to the SMB protocol.

  Therefore, even if a plurality of hosts transmit the CMD 56 including the SMB protocol at the same time, the protocols are not mixed by the exclusive control by the file system controller 70, and no contradiction occurs in the file system. That is, simultaneous access from a plurality of hosts can be made possible while protecting the file.

[Fourth Embodiment]
Next, a communication device and a control method thereof according to the fourth embodiment will be described. In this embodiment, the wireless LAN chip also functions as the file system controller 70 in the second and third embodiments. Hereinafter, only differences from the second and third embodiments will be described.

  FIG. 19 is a block diagram of a memory card according to the present embodiment and a digital camera in which the memory card is inserted.

  As shown in the figure, the memory card 20 according to this embodiment includes the file system controller 70 described in the second and third embodiments in the wireless LAN chip 21 in the configuration of FIG. 1 described in the first embodiment. It is provided.

  As described above, if the host (wireless LAN chip 21) has a margin for processing the SMB protocol encapsulated in the CMD 56, this function can be executed by the host without providing the file system controller 70 separately. . In this case, the number of chips can be reduced.

[Modifications, etc.]
As described above, the communication device 20 according to the embodiment includes the first interface 35, the wireless communication unit 21, and the memory unit 24. The memory unit 24 includes a first region PT1 used for the first access from the first interface 35 and a second region PT2 used for the second access from the wireless communication unit 21. Writing to the second area PT2 by the first access and writing to the first area PT1 by the second access are prohibited.

  This allows simultaneous access from a plurality of hosts and prevents data from being destroyed by writing data in the same area. As a result, the usability of the communication device can be improved.

  In addition, the said embodiment is only an example and various deformation | transformation are possible. For example, the NAND flash memory 24 may be another flash memory such as a NOR flash memory, or may be a semiconductor memory other than the flash memory. In the above embodiment, an example of a card device has been described. However, the memory card 20 may be a memory built in a host such as the digital camera 10. Furthermore, the memory is not limited to the SD interface.

  Furthermore, although a digital camera and a wireless LAN have been exemplified as hosts, a personal computer, Bluetooth (registered trademark), a television, a PDA, or the like may be used. Furthermore, the protocol for controlling the file in the third and fourth embodiments may be other than SMB, FTP, and WebDAV. That is, as a command encapsulated in a command defined in the SD interface, a command according to another appropriate protocol different from the SD interface can be selected.

  In the first embodiment, the case where one partition is assigned to one host has been described as an example. However, if there is room in the partition, a plurality of partitions may be assigned to one host. In the first embodiment, each host has been described with respect to a case where writing is prohibited but reading is permitted except for the assigned partition. However, reading as well as writing may be prohibited.

  Furthermore, the above-described embodiments can be implemented in combination as much as possible, and can be implemented alone as much as possible. Further, the order of the operations described using the flowcharts in the above embodiment can be changed as much as possible.

That is, the said embodiment contains the following. That is,
1. The first interface (I / F35 @ FIG. 1), the wireless communication unit (wLAN21 @ FIG. 1), and the first area used for the first access from the first interface (PT1 @ FIG. 3, or R1 @ 13) and a memory unit (NAND24 @ FIG. 1) having a second region (PT2 @ FIG. 3, or R2 @ FIG. 13) used for the second access from the wireless communication unit, A communication apparatus in which writing to the second area by the first access and writing to the first area by the second access are prohibited.
2. In 1 above, each of the first and second areas has a table (FAT1, FAT2 @ FIG. 3) for managing information in the first and second areas by a file system.
3. In the above 1 or 2, the memory unit further includes a third area for holding information (MBR @ FIG. 3) indicating that the first and second areas are included.
4). In 1 above, the first and second accesses are arbitrated, the writing by the first access is executed to the first area (R1 @ FIG. 13), and the writing by the second access is performed by the second area. A controller (file system controller 70 @ FIG. 8) that executes (R2 @ FIG. 13) is further provided.
5. In 4 above, the controller converts at least one of the addresses when the first and second accesses are made simultaneously to the same address.
6). In the above item 4, the first and second accesses are performed by an SD command encapsulating a protocol for performing file control.
7). In the above 6, the SD command is CMD56 in the SD interface standard, and the protocol is at least one of SMB (Server Message Block), FTP (File Transfer Protocol), and WebDAV (Web-based Distributed Authoring and Versioning). It is.
8). In the above 6 or 7, the first interface is an SD interface, and the file system controller extracts the protocol from the received first and second accesses, and issues a command to the memory unit according to the protocol.
9. In the above 4 to 8, information in the first and second areas is managed by the same table (FAT1, FAT2 @ FIG. 10) by the file system.
10. In the above 2 or 9, the file system is a FAT (File Allocation Table).
11. Reading first information (MBR @ FIG. 3) indicating that the memory section has first and second partitions (PT1, PT2 @ FIG. 3) from the first area of the memory section; Based on the first information, the first host (DSC10 @ FIG. 1) reads out a first table for managing the first partition from the first partition based on the MBR @ FIG. 3) and the first information. And a second host (wLAN @ FIG. 3) having a wireless communication function reading a second table for managing the second partition by a file system from the second partition.
12 In 11 above, the first host is allowed to write to the first partition, and the second host is prohibited from writing to the second host, and the second host is allowed to write to the second partition, Writing to the first partition is prohibited.
13. From the first host (DSC10 @ FIG. 1), receiving a write access to the first address area (R1 @ FIG. 12) in the memory unit, and from the second host (wLAN @ FIG. 3) having a wireless communication function, For receiving the write access to the first address area (R1 @ FIG. 12) and the access from at least one of the first and second hosts, the write destination is from the first address area. And a step of changing to a second address area (R2 @ FIG. 13) different from the first address area.
14 In the above 13, the information in the first and second address areas is managed by the same table (FAT1, FAT2 @ FIG. 10) by the file system.
15. In the above item 13 or 14, the access from the first and second hosts is performed by an SD command encapsulating a protocol for performing file control.
16. 15. In the above 15, the SD command is CMD56 in the SD interface standard, and the protocol is at least one of SMB (Server Message Block), FTP (File Transfer Protocol), and WebDAV (Web-based Distributed Authoring and Versioning). It is.
17. In 15 or 16, the first interface is an SD interface, and the file system controller extracts the protocol from the received first and second accesses and issues a command to the memory unit according to the protocol.
18. In the above 11 or 14, the file system is FAT.
Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10, 60 ... Digital camera 11, 36, 71 ... SD host interface, 12, 33 ... CPU, 20 ... Memory card, 21 ... Wireless LAN chip, 22, 35 ... SD device interface, 23 ... NAND controller, 24 ... NAND Type flash memory, 30 ... baseband chip, 31 ... physical part, 32 ... MAC part, 34 ... memory controller, 37 ... SDRAM, 38 ... NOR type flash memory, 40 ... RF chip, 41 ... RF part, 50 ... antenna, 61 ... Access point, 70 ... File system controller

Claims (6)

A first interface;
A wireless communication unit;
A memory unit including a first area used for first access from the first interface and a second area used for second access from the wireless communication unit; The communication apparatus is characterized in that writing to the second area by and writing to the first area by the second access are prohibited. The communication apparatus according to claim 1, wherein each of the first and second areas has a table for managing information in the first and second areas by a file system. The communication apparatus according to claim 1, wherein the memory unit further includes a third area that holds information indicating that the first and second areas are included. Reading first information indicating that the memory unit has first and second partitions from a first area of the memory unit;
A first host reading from the first partition, based on the first information, a first table for managing the first partition by a file system;
A second host having a wireless communication function based on the first information reads a second table for managing the second partition by a file system from the second partition. Control method of the device. The first host is allowed to write to the first partition and prohibited to write to the second partition,
5. The communication device control method according to claim 4, wherein the second host is allowed to write to the second partition and is prohibited from writing to the first partition. Receiving a write access to the first address area in the memory unit from the first host;
Receiving a write access to the first address area from a second host having a wireless communication function;
Changing the write destination from the first address area to a second address area different from the first address area for the access from at least one of the first and second hosts. A method for controlling a communication device.

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